Surfacing materials of various types have been known for many years, including high pressure decorative laminates and low pressure laminates. The former are formed of a plurality of thermoset resin impregnated paper sheets, the core sheets being impregnated with phenolic resin and the surface sheet or sheets being impregnated with melamine resin. These products have achieved great popularity and success over the years and have been long used as countertops, tabletops, wall coverings, etc.
Low pressure laminates are usually based on thermoset melamine resin impregnated facing sheets, with backing substrates formed of a wide variety of materials. Low pressure laminates are also used as wall panelling, and simulating wood in the manufacture of lower cost furniture, etc., and do not possess all of the admirable qualities of high pressure decorative laminate.
More recently, products of the CORIAN.RTM. and FOUNTAINHEAD.RTM. type have entered the marketplace and these have achieved wide acceptance as countertops and the like in kitchens and bathrooms in particular. Some of these materials, hereinafter generically referred to as "solid surfacing material", were originally designed to simulate stone products such as marble and granite, but now come in a wide variety of patterns. These solid surfacing materials are normally formed in thick slabs of thermoset acrylic or thermoset polyester, filled with various fillers including ATH, ground stone, etc. These products have a deep semi-translucent.sup.1 and lustrous appearance and are highly desired among designers and consumers, but on the other hand are very expensive, indeed usually more expensive than natural marble and granite. FNT .sup.1 What is meant by "deep semi-translucent" is that these products, while opaque to the passage of light therethrough, can nevertheless be seen into to an extent, and give the appearance of three-dimensional depth.
Solid thermoset surfacing materials of this type are normally formed in thick slabs, and so material costs are high on an area-of-coverage basis. Moreover, fabrication into products and installation of products based on these solid surfacing materials, including kitchen and bathroom countertops, involve a considerable amount of skilled manual labor, which further drives up the costs of these products on an installed basis.
More recently, General Electric has entered the marketplace with a product called NUVEL.TM. which is believed to be an extruded thermoplastic product containing a thermoplastic polyester, i.e. polyethylene terephthalate and/or polybutylene terephthalate, and a polycarbonate, filled with barium sulfate. We are aware of a General Electric patent in the name of Fisher et al, U.S. Pat. No. 5,149,734, which discloses a molding material which is a blend of polybutylene terephthalate and polyethylene terephthalate, filled with 30-85%, based on the total weight, of barium sulfate, said to have special utility for the injection molding of articles such as tableware including dishes, bowls or mugs; billiard balls, poker chips, paper weights, wall or floor tiles and the like, and which also may be used to mold circuit boards or panels. The composition is said to produce molded objects having a smooth and glossy surface, a ceramic-like feel and appearance, superior stain resistance, opacity to x-rays, freedom from warpage, excellent creep resistance, a low coefficient of thermal expansion and a high heat distortion temperature.
DE 2 024 940, published Dec. 2, 1971, discloses a blend of thermoplastic molding materials so as to cast a clear lens of high transparency. The resultant lens material, said to be useful in the lighting sector, for household optical purposes, or for the production of household vessels, is also said to have good heat resistance in addition to a high degree of transparency. The polymers to be blended are styrene-maleic acid anhydride copolymers and methyl methacrylate polymers. Styrene-acrylonitrile copolymers can be added to the molding materials to increase pourability for casting.
There is still a need for an improved, lower-cost, thermoplastic sheet for use as a surfacing material which can replace solid surfacing materials of the FOUNTAINHEAD.RTM. and CORIAN.RTM. type in at least some of their environments, and which has a deep semi-translucent appearance similar to such solid surfacing material and a comparable surface hardness.